Complications in the central nervous system during chemotherapy for childhood acute lymphoblastic leukemia: JACLS ALL-02 study

We evaluated central nervous system (CNS) complications treated under the ALL-02 protocol of the Japan Association of Childhood Leukemia Study (JACLS) from April 2002 to March 2005. According to NCI Toxicity Criteria, 17 events of grade 3 and 4 CNS complications were reported in 15 out of 541 patients. Out of these CNS complications, leukoencephalopathy was seen in 5 patients; seizure in 5; cerebrovascular disease in 3; conscious disturbance in 2; and hypertensive encephalopathy and reversible posterior leukoencephalopathy syndrome in one patient each. The complications were intensively observed during induction therapy and the last of the early phase chemotherapy. The protocol treatment was stopped or modified in most patients after CNS complications. MRI imaging demonstrated no improvement in one patient with leukoencephalopathy who developed an isolated CNS relapse, while other patients were alive and remain in their first complete remission without any neurological sequelae. Further studies will be required to analyze risk factors for CNS complications during chemotherapy not accompanied by irradiation and to establish alternative treatments after the appearance of such CNS complications.